In the construction of precision machine components, such as a right circular cylinder and shaft rotating at high speed in a gyroscope, a hydraulic actuator or bearing in a magnetic disc memory, the dimensions of the diameter, length, cylindricity and squareness all become critical Careful machining, lapping and measuring are necessary to achieve the demanded accuracy that is typically within a few microinches.
The processes do not readily lend themselves to inexpensive mass production of such components because of the repetitive dimensional checking and finishing, such as lapping and honing, that can be required. This is especially true with elements that rotate on gas films and must avoid interference with mating parts. Such elements operate with little clearance and need to be held to close tolerances to achieve the stability and reliability necessary.
Precision and fabrication efficiency, which can be achieved with existing production equipment, can also be limited by the design of the components. Although redesign can often aid the manufacturing processes, changes in either a component configuration or its processing may bring about other problems.